1887 P - Thoughts

I've seen this before, probably a wood chip or splinter got caught up on a greased die, I say this because, I've seen Morgans with this sort of look and with the actual wood splinters are still embedded in the coin surface after striking, most however, show a rough pattern like wood pulp similar to the above two coins pictured.

Still just my theory, I imagine the mint workers would move the dies in wooden boxes or crates when storing them or working on them, the dies were oiled and greased to prevent rusting, so during change overs on the coining presses, I think this is where the foreign material was picked up, wood splinters even small ones would stick easily to a die and may go unseen by a mint worker. Remember all tools were wooden handled too back then, they also kept a lot of wood around for stoking fires in the mints smelting and in general to keep warm especially in Philly in the winter!